This invention relates to an image transmission system for transmitting image data added with code data.
For the image transmission systems which can send still images by radio, efforts are now underway to increase the transmission rate and produce an error-free system, as discussed by Toyota Honda, "Still Video Transceiver over the General Telephone Networks", Technical Report of the Institute of Electronics, Information and Communication Engineers, Vol. 88, No. 197, pp. 27-34. FIG. 1 shows the construction of the conventional image transmission system. In FIG. 1, reference numeral 21 denotes an image transmission device, and 22 denotes a video floppy disk player, which is played to transfer still image data recorded on a video floppy disk to the image transmission device 21. Reference numeral 23 denotes an image memory part of the image transmission device 21, and temporarily stores still image data supplied from the video floppy disk player 22.
The operation of the image transmission system arranged as mentioned above will be described with reference to FIGS. 2 and 3. A video disk containing images acquired with an electronic still camera is loaded on the video floppy disk player 22 (steps 91, 92). Then, the operator, while looking at a monitor screen, operates the video floppy disk player 22 to select an image he wishes to transmit (step 93). Now, the image transmission device 21 issues a command that data transmission of the selected image in the video floppy disk player 22 should be started (step 94), and a transmission process of image data is executed (step 95).
Description will be made in detail of the selection process (step 93) of images to be transmitted. Let i denote an image number in the floppy disk, and j denote the total image data amount stored in the image memory part 23. They are initialized to i=1 and j=0 (step 96). A decision is made whether to select an image i (step 97), and if the decision is YES, the process proceeds to step 98, and if the decision is NO, the process moves on to step 104. When an image i is selected at step 97, the image transmission device 21 issues a command that the selected image i should be transferred from the video floppy disk player 22 to the video transmission device 21 (step 98), and image data of the image i is transferred to the video transmission device 21 (step 99). In the image transmission device 21, the image data supplied from the video floppy disk player 22 is data compressed (step 100). At this point, data amount of the compressed image i is added to j, and the resultant j is compared with the memory capacity of the image memory part 23 (step 102). If j is now larger than the memory capacity of the image memory part 23, the process proceeds to step 94, and if j is not larger, the process advances to step 103. When j is smaller than the memory capacity of the image memory part 23, data of the compressed image i is transferred to the image memory 23 (step 103). Then, i is added with 1 (step 104), and the resultant i is compared with the number of frames recorded (step 1050. If i is larger than the number of frames recorded, the process moves on to step 94. If i is not larger, the process goes to step 97 and this process is repeated until the number of frames to be transmitted are stored, thereby the image transmission device gets to a state ready for transmission.
However, a problem with the above-mentioned conventional arrangement is that only video data recorded with an electronic still camera can be transmitted, but it is impossible to transmit code data which includes additional information such as an object of video recording, recording conditions, or messages about the condition of the site.
This disadvantage makes the conventional image transmission system inconvenient for recording the condition of a diameter area with a camera and transmitting information on the disaster along with the images from the site to the central station.